Pete's Posts Blog

Monthly Archives: April 2014

On-chip interconnects have not been scaling at the same speed as transistors. When TSMC went from 20nm to 16/14nm, for example, they decided to replace the bulk MOSFET with a FinFET, but they left the interconnect stack as is. In part, interconnect scaling has been slow because companies don’t want to make too many major changes at the same time and introduce risk. Costs, of course, are also an issue. “When you’ve got ten layers of metal and let’s say six layers of those are close to minimum pitch, it gets very expensive once you start doing double patterning,” said Dr. Deepak Chandra Sekar, general co-chair of the upcoming 2014 IITC/AMC joint conference. “With the interconnect layers, people want to save litho costs. That’s one reason they are not scaling as much as they used to.”

But the major reason is that it’s difficult to make interconnects much smaller without introducing significant increases in resistivity. “If you scale down and your resistivity goes up exponentially, it can be a problem,” Sekar said. “Copper resistivity shoots up when you scale it down because of surface scattering, grain boundary scattering and interface roughness.”

The 17th annual International Interconnect Technology Conference (IITC) will be held May 21 – 23, 2014 in conjunction with the 31st Advanced Metallization Conference (AMC) at the Doubletree Hotel in San Jose, California. It will be preceded by a day-long workshop on “Manufacturing of Interconnect Technologies: Where are we now and where do we go from here?” on Tuesday, May 20.

Sekar highlighted a number of papers that will be presented this year. Many of them focus on new materials that could lead to reduced resistivity and enable further interconnect scaling. “There is a lot of excitement about carbon and carbon-copper composites eventually replacing copper,” he said. “At IITC this year, we have a couple of papers, one on graphene showing lower resistivity than copper, and then one on carbon nanotubes showing good resistivity as well. They are still a bit far out in the sense that there’s a lot more process integration work that needs to be done because these are proof of concept demos, but they show that there might be more beyond copper.”

In a paper from AIST, titled “Sub 10nm wide intercalated multi-layer graphene interconnects with low resistivity,” work will be presented that demonstrates 8nm wide 6.4nm thick graphene interconnects with a resistivity of 3.2uohm-cm, which is significantly better than copper with similar dimensions. This milestone for graphene interconnect research is expected to motivate the process integration research that is required to take the technology to the next level.

8nm wide graphene interconnects

Carbon nanotubes (CNTs) have been explored as a material for vertical interconnects for many years since they can handle higher current densities than copper and offer ballistic transport. A paper from imec titled “Electron Mean Free Path for CNT in Vertical Interconnects Approaches Copper,” work will be presented that demonstrates a 5x improvement in electron mean free path for CNTs compared to previous work. The CNT mean free path of 24-74nm approaches copper. Contact resistance is improved significantly compared to previous work as well.

Carbon Nanotube (CNT) vias in integrated structures

Another challenge to scaling of interconnects: reliability. Both time-dependent-dielectric-breakdown (TDDB) and electromigration lifetimes for interconnects drop rapidly when scaled. In work to be presented at IITC/AMC, IBM and Applied Materials will present a multi-layer SiN cap process is developed that shows higher breakdown and lower leakage compared to conventional SiCNH caps. Selective cobalt caps in combination with the multi-layer SiN cap are shown to provide a 10x improvement in electromigration lifetimes. Wrap-around cobalt liners in combination with the cap layer schemes are shown to provide a 1000x improvement in electromigration lifetimes. The paper is titled “Advanced Metal and Dielectric Barrier Cap Films for Cu Low k Interconnects.”

Of course, an alternative to making everything smaller by scaling is to go 3D. That will be addressed by a variety of papers, including one from CEA-Leti focused on 3D monolithic integration. While most of today’s through-silicon vias (TSVs) are in the 5µm range, monolithic 3D technologies offer TSVs in the 50nm range, which allows dense connectivity between different layers in a 3D-IC. In the Leti paper, such dense connectivity is shown to provide 55% area reduction and 47% energy-delay product improvement for a 14nm FPGA design. Transistor technologies that allow monolithic 3D integration are experimentally demonstrated. “When you make the TSVs smaller and smaller, you can reduce the length of on-chip wires as well by taking what’s on a single now and stacking them into two layers,” Sekar said. “That might save a lot of power and area. There’s been a lot of talk about monolithic 3D, but these are some of the first few experimental demonstrations showing that it’s possible.”

Dr. Roawen Chen, senior vice president of global operations at Qualcomm, will provide the keynote talk at The ConFab 2014 this year. The event will be held June 22-25 at The Encore at The Wynn in Las Vegas.

In his talk, Dr. Chen, will describe how the increased performance and the rapid shift from traditional handsets to consumer computing device post a number of manufacturing and supply chain challenges for fabless chip makers. He says the scale of the challenges also creates an “extreme stress” for the existing foundry/fabless model to defend its excellence in this dynamic landscape. In this talk of “what’s on our mind?” he will deliberate on a number of headwinds and opportunities.

In his role at Qualcomm, Roawen oversees the worldwide operations and supply chain, silicon and package technology, quality/reliability, and procurement functions for the Qualcomm semiconductor business. He has overall responsibility for driving the global integrated fabless strategy and execution.

Roawen is an experienced leader in all aspects of semiconductor operations and supply chain management with a solid background in leading large-scale fabless operations. In addition to his strong technical depth, he has proven experience in building close supplier and vendor relationships and executing to support customer demand and product development. Prior to Qualcomm, Roawen was Vice President of Manufacturing Operations at Marvell Semiconductor in Santa Clara, California. During his more than 12 years at Marvell, Roawen held a variety of leadership roles, including Vice President and General Manager of the Communications and Computing business unit and Vice President and General Manager of the Connectivity business unit. He has also served in management roles in Marvell’s Foundry Operations and Manufacturing Technology groups.

Prior to Marvell, Roawen held technical positions at TSMC-USA and Intel. He earned a bachelor’s degree in Physics from National Tsing-Hua University in Taiwan, a master’s degree in Materials Science from the University of California, San Diego and a PhD in Electrical Engineering and Computer Science from the University of California, Berkeley.

The semiconductor market will continue at a steady growth rate for the next several years. For a semiconductor company to achieve significant growth in this ultra-competitive environment, it needs to identify market opportunities and predict the future, in terms of markets, both regionally and globally, anticipate technological advancements, as well as envision new applications. At The ConFab in June, Session 1 will provide an overview of these critical issues.

The presenters will be:

Vijay Ullal, COO, Fairchild Semiconductor

Dave Anderson, President and CEO, Novati Technologies

Gopal Rao, Senior Director Business Development, SEMATECH

Adrian Maynes, Program Manager, F450C

Bill McClean, President, IC Insights

Here’s an overview of what each presenter plans to cover:

The Economics of Semiconductor Manufacturing and the Escalating Cost of R&D

Vijay Ullal, COO, Fairchild Semiconductor

While innovation in semiconductor technology is driving change in industries from automotive to mobile, and the sophistication of computers, mobile devices, automobiles, industrial systems and consumer goods evolves, greater pressure is placed on semiconductor research and development (R&D) as well as Supply Chain Management (SCM). Now, the bar has been raised from not only delivering leading-edge technology, but also to delivering far greater value to an organization. This presentation will use examples of to focus R&D as well as revitalize your supply chain in order to highlight your competitive advantages, and better meet these market place demands by moving beyond the “product sell” to an approach that focuses instead on the key attributes customer’s value.

More-than-Moore: A New Era of Innovation

Dave Anderson, CEO, Novati Technologies

The semiconductor industry has focused on Moore’s Law for more than 40 years in its quest for ever shrinking geometries to squeeze more transistors on a chip and improve device speed and performance. Digital microcircuits have benefited immensely from this extreme scaling but, with fewer companies having the ability to support further scaling, More-than-Moore (MtM) has emerged to apply decades of semiconductor process knowledge to novel applications to produce state-of-the-art biochips, sensors, actuators, imagers and more. Perhaps most importantly, MtM technology is enabling companies to build these components more cost-effectively and with better performance and smaller size than ever before.

Providing a significant advantage over traditional volume foundries, a new wave of boutique nanotechnology development centers is in a unique position to integrate new materials with custom processes. This provides a rapid acceleration of development and production for world-leading ideas and breakthrough MtM products.

The result is a new era of innovation that couples the best of the past with future demands to create valuable applications and markets. The era for enabling the most rapid, but affordable, new product development and deployment has begun.

Enabling the Supply Chain to Accelerate R&D

Gopal Rao, Senior Director of Business Development, SEMATECH

There is a push/pull market energy that is now, more than ever, influencing the device makers, suppliers and the consumers who are thirsty for innovative mobile computing and connected devices. The IC industry has relied on a push based roadmaps to bring products to market. It is important that we acknowledge that the consumer appetite for innovative and cool products has created a pull system that may be considered a roadmap. The challenge facing the whole IC industry is how to recognize, rationalize and leverage these push/pull roadmaps. This talk examines this IC industry challenge and opportunity, specifically in moving the vast supply chain to feed into this fast moving market. The pace of R&D through entire supply chain is essential in staying ahead of the curve and driving down cost of technology and manufacturing. Radical, innovative product designs to meet consumer demand will push into the IC supply chain the need to identify and develop significant cost/performance improvements in IC device performance. What are these improvements? Are the current roadmaps highlighting them or do we need to better, integrated intelligent roadmap that helps the supply chain stay on treadmill of innovation and cost reduction?

It is widely accepted that in the next few years the semiconductor industry will begin to transition to the next generation 450mm wafer size. Experts throughout the semiconductor industry are striving to make 450mm a reality from a technical and manufacturing standpoint. Along with the increase in wafer size, the industry is closely examining impacts to the facility infrastructure, as merely scaling the manufacturing process is not a practical option. The size of the 450mm facility infrastructure and its associated utility consumption projections would simply exceed affordability and resource availability.

The facility experts involved in establishing and later implementing 450mm infrastructure requirements are facing the same degree of challenges as the IC and equipment manufacturers. For the first time in semiconductor history, facility professionals are collaborating closely with the industry’s top five consolidated IC manufacturers to bring their collective expertise to bear on the most pressing 450mm fab issues. With special focus on safety, cost, schedule, sustainability, and environmental footprint, this global consortium of industry specialists is aiming to reduce the cost of production, increase productivity for manufacturers, and reduce the environmental footprint on a per chip basis

This presentation will address these various infrastructure requirements and potential issues for a more sustainable manufacturing process. The session will be co-presented by leaders of the Facilities 450mm Consortium (F450C) and the Global 450mm Consortium (G450C). These two groups are collaborating as experts from across the entire supply chain to ensure a smooth transition to the 450mm technology.

Major Trends Impacting the IC Industry of the Future

Bill McClean, Presdient, IC Insights

IC Insights forecasts that 2014 will continue the integrated circuit industry cyclical upturn that began in 2013. This cyclical upturn is expected to gain momentum over the next several years, resulting in a 6.4% IC market CAGR over the 2013-2018 time period, which would be more than 3x the 1.7% CAGR the IC market displayed from 2007-2012. Although a high level of uncertainty still looms over the global economy, sales of smartphones and tablet PCs continue to soar. IC Insights will present its forecast for the IC market in the context of the IC industry cycle model. In order to make sense out of the current turmoil, a top-down analysis of the IC market will be given and include trends in worldwide GDP growth, electronic system sales, and semiconductor industry capital spending and capacity.